Many media processing devices are configured to utilize memory cards or other types of removable storage devices, including microdrives, where the term microdrive refers to removable storage devices utilizing either rotating magnetic media, such as a hard disc drive (HDD), or rotating optical media. Flash drives, having a universal serial bus (USB) connector, are another type of removable solid-state memory device in common use for storage of media files.
In an exemplary application, a digital camera such as model V610, manufactured by Eastman Kodak Company, Rochester, N.Y., includes a memory card slot adapted for insertion of a memory card that may include, for example, Secure Digital (SD) or Multimedia Card (MMC). Digital images captured by the digital camera are stored in the memory card. The memory card can then be removed from the digital camera and inserted into a memory card slot associated with another processing device such as a personal computer, such that the other processing device can be used to view, print, archive, email, upload, transmit or otherwise process the images stored on the memory card.
In another exemplary application, a portable music player such as model LDP-200, manufactured by Lexar Media, Inc., Fremont, Calif., includes a memory card slot adapted for insertion of an SD card. Music files (MP3, WAV, etc.) that have been saved to the SD card by another processing device, such as a personal computer, can be played back by the portable music player.
Prior to accessing any of the contents of the removable storage device, the processing device must first scan the storage device to determine its contents. This operation typically takes place during power-on of the processing device or immediately following insertion of a removable storage device into the powered-on processing device. The results of this scan are then temporarily cached in the processing device's internal memory as a file system database structure for the removable storage device and the procedure is often referred to as mounting the file system. This cached file system then permits quick access to any of the removable storage device's files by the processing device.
Unfortunately, this process currently needs to be repeated each time that the media-processing device is powered on or each time that a removable storage device is inserted into the powered-on processing device. As the capacity of removable storage devices continues to increase, the time required to mount their associated file systems also increases, with a corresponding negative impact on the consumer's user experience with the processing device.
U.S. Pat. No. 6,862,604 discloses a method involving the generation and maintenance of a file usage data structure by the memory card controller. The file usage data structure is resident on the memory card itself and is updated by the memory card controller following each file change operation such as writing a new file to the card or modifying or deleting an existing file. The memory card controller is configured to report the contents of the file usage data structure to the processing device when requested. The method taught by this disclosure suffers from at least two drawbacks. First, it imposes the use of a predetermined file usage data structure, thereby limiting implementation flexibility by processing device manufacturers. Second, it fails to provide a simple method to allow a processing device to quickly determine whether or not the contents of the storage device have changed since the last time it was used by a particular processing device.
Therefore, a need exists for a means to enable a processing device, that is operably connected to a removable storage device, to quickly and easily determine whether or not the contents of the removable storage device were changed since it was last used by the processing device. The availability of such a means would enable the processing device to instantly mount the file system of the removable storage device in the event that no changes were made to the contents of the removable storage device since it was last used by the processing device.